Our U.S. Pat. No. 5,501,035, entitled "Trellis Wire Support Assembly," includes a background discussion of vertical trellis system design, including basic trellis systems and design consideration therefor. This background discussion is incorporated herein. Common to many types of vertical trellis systems are stakes that have a basic T-formation or multiple T-formation, with one or more cross arms secured to an upright stake. Trellis and fruiting wires are strung between the cross arms of spaced apart stakes to create the necessary support structure for grapevines and orchard trees. While the present invention has utility for supporting grapevines and orchard trees, the discussion herein will be limited to grapevines because that is the context in which the present invention was developed.
Grapevine foliage grows either up past the trellis wires or down past the trellis wires, depending on the type of trellis system, which is dictated by the type of grape. With a Geneva Double Curtain system, grapevines grow down over trellis wires, whereas with a straight or lyre Canopy system, grapevines grow up past trellis wires. With both types of trellising systems, as well as with other systems, it is necessary for mechanical harvesting and pruning equipment to maneuver between trellis wires, which requires that the trellis wires be properly set up at a relatively constant height above the ground, allowing machinery to move relatively quickly down a trellis row and ccurately perform its functions. This requires the cross arms that support the wires to maintain their normal orientation to the stakes, typically 90.degree..
A common T-shaped grapevine stake is shown in FIG. 1. Stake 10 is driven into ground 12 and supports a cross arm 14 at approximately a 90.degree. angle to stake 10. Trellis wires (not shown) are supported at the outer reaches of cross arm 14 and would extend into and out of the figure, supported by additional stakes. A grapevine 16 grows up and around stake 10 and the trellis wires. When the grapevines are fruiting, grape bunches hang down below the cross arm and trellis wires and mechanical harvest equipment moves longitudinally between adjacent trellis rows to shake and knock grapes from the vines. Grapevine pruning equipment moves along a trellis row in a similar manner to cut prune shoots from the vines during the grapevines dormant season.
FIG. 1 shows schematically part of a mechanical pruner 20 that has shears 22, 24 that move below and above cross arm 14 and prune the grapevine during its dormant season. Both pruning and harvesting machinery need to move at a fixed distance from the cross arms of each stake in order to properly perform their functions. Yet, the weight of the grapes, as well as other forces, place great strain on the connection of the cross arms to the stakes and, as a result, this connection needs to be extremely secure in order to resist these forces and thereby maintain the angle between the cross arm and the stake so that machinery with pre-positioned components can maneuver between trellises.
When the weight of the grapes causes the cross arms to sag, pivot or tilt, workers have to manually adjust and resecure the cross arms at proper 90.degree. angles. This is both time consuming and adds significant expense to the process.
Our company, Vineyard Industries, Inc. of Windsor, Calif., USA, manufactures and sells a dimpled cross arm that is shown in FIGS. 2-5, upon which the present invention is an improvement. Referring to FIG. 2, dimpled cross arm 30 includes an upper raised rib 32 and a lower raised rib 34, each of which extend along the length of cross arm 30. A series of five holes 36, 38, 40, 42, 44 are provided at approximately the midpoint of cross arm 30 for receiving the legs 46, 48 of an off-set U-bolt 50. Cross arm 30 is secured by U-bolt 50 to a stake 52 that is T-shaped in cross section. The series of holes are provided to accommodate different width U-bolts, each specifically designed for different width stakes. Cross arm 30 also has an upper series of dimples 68 and a lower series of dimples 70, which are discussed later.
Referring to FIG. 3, stake 52 includes an upright side edge 60 that butts against cross arm 30, between dimples 70 (and dimples 68), when the cross arm and stake are secured together. Stake 52 also includes a center trunk 62, around which wraps leg 46 of bolt 50, and an opposite upright side edge 64, which anchors the apex 66 of bolt 50. With this design, stake 52 is held at three points by U-bolt 50 and is securely held to cross arm 30 and oriented with trunk 62 generally parallel with the cross arm.
Upper dimples 68 and lower dimples 70 are aligned with and are equally spaced from each other in a manner creating a uniform set of vertical channels 71 between the dimples, which channels provide different options for positioning side edge 60. The particular upright channel that side edge 60 abuts against is dependent on the size of the stake, which dictates the size U-bolt required. The purpose of the dimples is to abut side edge 60 and prevent cross arm 30 from teetering due to the force of the weight of the grapes.
Referring to FIGS. 4 and 5, for any given cross arm 30, significant vertical forces, indicated by arrows 73, can be exerted on the outer reaches of the cross arms by the weight of the grapes. Forces 73 tend to cause cross arm 30 to tilt relative to stake 52 even though U-bolt 50 securely holds the cross arm to the stake. The purpose of dimples 68, 70 is to resist tilting of cross arm 30 by creating a raised obstruction to tilting of cross arm relative to the side edge 60 of stake 52. Since U-bolt 50 securely holds side edge 60 against cross arm 30, cross arm 30 can not tilt to a significant degree relative to side edge 60 because dimples 68, 70 butt against the side edge, thereby preventing further tilting movement. However, in field practice it has been discovered that the performance of the dimples can be improved. It is an object of the present invention to prevent tilting of the cross arm to any significant degree.
Our company has also manufactured and sold in the past a slotted cross arm, the design for one of which is shown in FIGS. 6-8. Referring to FIGS. 6 and 7, slotted cross arm 76 includes a curved upper section 78 with a forward bulge 80 and a backwardly turned edge 82. A transverse slot 84 is created in bulge 80 for receiving a side edge of a grape stake. Cross arm 76 also includes a lower forwardly turned flange 86 that has a notch 88 cut therein. Notch 88 is aligned with slot 84 and also receives the side edge of a grape stake.
Cross arm 76 also includes a pair of bolt holes 90, 92 and a longitudinal slot 94, for receiving the legs of a U-bolt. One leg of a U-bolt extends through either hole 90 or 92, depending on the width of the U-bolt, and the other leg extends through longitudinal slot 94. Each hole 90, 92, in combination with slot 94, can accommodate different size U-bolts due to the extra width afforded by longitudinal slot 94. This allows cross arm 76 to be mounted to grape stakes of different widths, each of which requires a particular width U-bolt.
As shown in FIG. 8, cross arm 76 is secured by U-bolt 100 to grape stake 96, which has an upright side edge 98 that fits within slot 84 and notch 88. U-bolt 100 has a first leg 102 and a second leg 104, which extend, respectively through hole 92 (not shown in FIG. 8) and slot 94. A short backing plate or strap 106 is provided across the back of hole 92 and slot 94, through which legs 102, 104 extend. Nuts 108 secure bolt 100 and backing plate 106 to cross arm 76 wherein all of the components are rigidly secured together. Slot 84 and notch 88 prevent side edge 98 of cross arm 76 from pivoting or tilting about stake 96 due to the close fit of the side edge within the slot and notch. While slot 84 and notch 88 work well to prevent pivoting of cross arm 76, the provision of slot 84 and notch 88 has been found to structurally weaken the cross arm in a manner that may result in bending or breakage of the cross arm.
The cross arm of the present invention improves upon this design by providing a cross arm connection to a grape stake that is rigid and durable and does not structurally weaken the cross arm.